The primary aim of this project is to determine whether there are differences across race and gender in nitric oxide (NO) production during stress, and whether these differences account in part for the race and gender differences seen in blood prerssure (BP) responses to stress (reactivity). Previous studies by ourselves and others suggest that NO may play an important role in blood pressure regulation, that stress-induced changes in plasma NO metabolites are inversely related to BP reactivity among premenopausal women, and that there may be racial differences in stress-induced changes in plasma NO metabolites which may account for racial differences in BP reactivity. In the proposed study, we will test young adults in a sample balanced for gender and race (white/black), using a standardized reactivity protocol and measuring plasma NO metabolites (nitrates/nitrites) before and after stress. Subjects will be put on a low nitrate/nitrite diet for two days prior to testing, in order to provide proper assessment on NO metabolites. We will also assess plasma estradiol levels in women, to more directly assess the potential relationship between estrogen levels and NO production. Our hypotheses for this study are: 1) NO production during stress is higher among whites than blacks, and higher among premenopausal women then men; 2) NO production is inversely related to blood pressure responses to stress; 3) Plasma estradiol levels in women will be directly related to NO production at rest and during stress; and 4) Differences in NO production during stress account in part for the race and gender differences seen in blood pressure reactivity. The results obtained from this study will be integrated with results from previous studies to provide an assessment of the role of NO in blood pressure regulation, which will lead to larger projects assessing the interaction of gender and race differences with other factors relevant to NO production and cardiovascular disease risk.